Patients with stroke often suffer chronic disability. This disability may be caused by damage to motor systems or damage to separate "intentional" systems. Intentional systems might be more successfully treated with rehabilitative therapy than the motor systems. A subset of chronic stroke patients show greater motor disability than would be expected from the degree if weakness they experience; these patients can improve function substantially following two weeks of a new type of rehabilitative treatment developed at UAB. In this study, we are characterizing by fMRI studies the patients most likely to benefit from this treatment, and investigating how intentional systems contribute to patient's deficits and their responses to treatment. Patients are asked to perform a simple motor task involving rotating or extending their hands while brain activity is imaged by functional MRI. The fMRI activation images are interpreted to determine which brain areas are involved in the motor task. Studies are performed just before the initial treatment and several weeks later. We are testing the basic repeatability of the functional imaging studies, to determine how variable activation patterns are in healthy volunteer subjects performing the same motor tasks in different experimental sessions several weeks apart. Thus far, we have performed studies on three patients and three normal subjects, and have demonstrated the ability to obtain useful activation images during the functional protocol, with the subject performing arm and hand motions. The repeatability testing now being undertaken will determine to what extent small changes in activation pattern occur normally, to establish a level at which changes observed in patients can be deemed significant.